Prior art lifting slings for lifting railroad traction motor assemblies as illustrated in FIG. 1 of the drawings, comprise a pair of main cables designated 10 and 12. Each of the main cables is formed of several parts (i.e., eight) of strand wire rope braided together and connected through thimble eyes 14 to a master link 16 at one end and to a steel hoist hook 18 at the other end.
The hooks are adapted to engage the outside rim of the pair of drive wheels 19 which are mounted on the shaft of the traction motor 20. A pair of auxiliary wire rope cables 22 extend between the master link and hooks 24 which engage eyelets in the motor casing to prevent the casing from rotating relative to the wheels during the lifting operation.
The chamfer at the outer rim of the drive wheels is not uniform from wheel to wheel with the result that a hoist book's purchase on the rim may be insufficient on some wheels allowing the wheel assembly to fall.
The energy stored in the wire cables as a result of elastic elongation during a lifting operation provides a hazardous situation should one of the hoise hooks slip off the wheel rim. The stored energy when released may result very rapid movement of one or more of the cables endangering any individual positioned near the traction motor assembly during the lifting operation.
There is a need for a sling assembly and method which overcomes the above problems.